This invention relates to a method and apparatus for measuring operational angles of driveline components to determine whether the driveline is properly balanced.
Most vehicle drivelines include drive axles that are connected to a driveshaft or other driveline component with a universal joint. Universal joints, or U-joints, are utilized on most vehicle drivelines. One common type of U-joint is known as a Cardon universal joint. In this type U-joint, two yokes each have two bore locations at diametrically opposed positions. The yokes are each mounted to two posts on a cross member. The combination allows the two yokes to move angularly relative to each other with respect to the center of the cross member.
The U-joint is typically utilized as a portion of a driveline for a vehicle, and allows two shaft components to be at different angles relative to each other to accommodate relative movement and angular misalignment. U-joint connections are used to interconnect drive axles that are not mounted to the vehicle in a common plane.
For example, a typical driveline with two drive axles includes the following connections. One drive axle has a center differential for driving a set of vehicle wheels. The center differential has an input and an output for driving connection to an input for a second drive axle. A driveshaft is used to connect the first axle to the second axle. One end of the driveshaft is connected to the output of the first axle with a U-joint assembly and the other end of the driveshaft is connected to the input of the second drive axle with another U-joint assembly. A driveline operational angle is defined as the angle between differential centerline and the driveshaft centerline. Preferably, the operational angle at one end of the driveshaft is equal or close to the operational angle at the opposite end of the driveshaft. If the angles are equal or close to each other, the driveline components are properly balanced. If the operational angles are not close to each other there is a mismatch. If the mismatch exceeds a predetermined limit, than the driveline components are not properly balanced, which can result in premature wear of the components. Unbalanced driveline components can also cause undesirable vibrations and noise.
For various diagnostic and control purposes, it would be valuable to be able to measure multiple driveline operational angles and compare them to each other to determine whether the driveline components are properly balanced. However, no simple method has been developed for measuring operational angles during the operation of a vehicle.
For the above reasons, it would be desirable to develop a method and apparatus for monitoring and measuring driveline operational angles during real time operation of the vehicle. The method and apparatus should be inexpensive and easily incorporated into existing driveline systems.
In a disclosed embodiment of this invention, a system measures multiple operational angles of a driveline assembly and compares the signals to each other to determine whether the angles and the respective driveline components are properly balanced. Different types of sensor assemblies can be used to measure the operational angles.
In a preferred embodiment of this invention, a driveline assembly includes a first drive axle with a first center differential having a first input and a first output. A second drive axle has a second center differential with a second input. A driveline component interconnects the first and second axles at opposing ends and defines a central axis. A first universal joint assembly connects a first end of the driveline component to the first output and defines a first operational angle between the first center differential and the central axis. A second universal joint assembly connects a second end of the driveline component to the second input and defines a second operational angle between the second center differential and the central axis. A sensor assembly is mounted adjacent to the driveline component to measure the first and second operational angles. The sensor assembly generates a first signal corresponding in magnitude to the first operational angle and a second signal corresponding in magnitude to the second operational angle.
Preferably, a processor is operationally linked to an indicator. The processor compares the first and second signals to each other to determine a mismatch ratio. The processor generates an activation signal to activate the indicator when the mismatch ratio exceeds a predetermined limit.
In another embodiment, the processor is operationally linked to an adjustment mechanism. The processor compares the first and second signals to each other to determine a mismatch ratio. The processor generates an activation signal to activate the adjustment mechanism, which adjusts a vehicle parameter to correct the first and/or second operational angles when the mismatch ratio exceeds a predetermined limit.
Various types of sensors can be used to measure the driveline operational angles. In one embodiment, accelerometers are mounted to each of the axles and acceleration due to gravity measurements are used to determine the operational angles. In another embodiment, fluid level sensors are used to determine the operational angles. Other sensors used to determine the operational angles include potentiometers, photo cell sensors, proximity sensors, non-contact magnetic sensors, and photo/digital imaging cameras, for example.
The method for determining operational angles of driveline components includes the following steps. A first axle assembly and a second axle assembly are interconnected by a driveline component having universal joint assemblies mounted at opposing ends. A first operational angle is measured between the first axle assembly and one of the universal joint assemblies and a second operational angle is measured between the second axle assembly and the other of the universal joint assemblies. The second operational angle is compared to the first operational angle to determine a mismatch ratio and an indicator signal is generated if the mismatch ratio exceeds a predetermined limit.
The subject invention provides a simple and easy method and apparatus for determining whether driveline components are properly balanced. The invention is easily incorporated into existing driveline systems and is easy to maintain. These and other features of the present invention can be best understood from the following specifications and drawings, the following of which is a brief description.